In the fermentation industry, yeast agglutination is an industrially important phenomenon, and the use of agglutinative yeast is being studied while much research is being undertaken to discover the cause of its agglutination. Yeast agglutination is known to be controlled by a plurality of genes, a relatively well researched example thereof being the agglutination gene called FL01, which is mapped on the right arm of yeast chromosome I.
Regarding the structure of the agglutination gene FL01 derived from the yeast Saccharomyces cerevisiae, it had been completely unknown, but in 1989 it was cloned for the first time by the present inventors et al., and its restriction enzyme cleavage map has been determined (Watari et al., Agricultural and Biological Chemistry, Vol. 53, No. 3, p.901-903, 1989). (Nevertheless, it base sequence was unknown).
We the present inventors reported that it is possible to convert non-agglutinative industrial yeasts into agglutinative yeasts for practical use by the introduction of the agglutination gene FL01 into various industrial yeasts (Watari et al., Agricultural and Biological Chemistry, Vol. 55, No. 6, p.1547-1552, 1991); however, it was not always possible to impart strong and stable agglutinative properties to all of the industrial yeasts.
We the present inventors thereafter diligently pursued research on the FL01 gene, and discovered that the gene that we the present inventors et al. had reported as being the FL01 gene (Watari et al., Agricultural and Biological Chemistry, Vol. 53, No. 3, p. 901-903, 1989) was not the intact FL01 gene as present on chromosome I of the yeast Saccharomyces cerevisiae strain ABXL-1D, but was the FL01 gene with a portion thereof deleted during maintenance of the plasmid containing the intact FL01 gene in Escherichia coli strain K12 (hereunder, this gene shall be referred to as FL01S).